Could you please post a full trace capturing the entire time that you are referring to

The trace excerpt posted just shows the 'Release Call' event - which happens at the very end of the line hangup process - and then a Line_Hangup COM command which would have been issued from some external script - but is made after the line has fully hung up already.

And entire trace excerpt posted only covers a 2 millisecond time range.

Here are some excerpts from traces supplied before from your system which show how fast call hangup is.

As you can see these actions take a small fraction of a second on a VoiceGuide system:

Example 1: Call hung up up by VoiceGuide:

VoiceGuide received confirmation from ISDN network that call was dropped within 50 milliseconds of call hangup being requested by the script, and then VoiceGuide released the call which was confirmed by Dialogic driver layer 5 milliseconds later.

VoiceGuide script drops the call 1 milliseconds after being advised that remote end hung up, confirmation of that is returned to the script from Dialogic 20 milliseconds later, and then performing a call release takes 5 milliseconds.